This research utilizes a variety of animal models to gain further understanding of the negative feedback controls that regulate body weight. In particular, the role of the cerebrospinal fluid (CSF) in controlling body weight is being assessed in chaired baboons. The normal relationship between CSF and blood parameters is assessed in several natural situations (fasting, after a meal, etc.), and the effect of artificial manipulation of the contents of the CSF is being determined upon acute and chronic feeding, maintenance of body weight, and various humoral parameters. Similar experiments are being carried out on rats. Additionally, the role of the autonomic nervous system is being determined on a variety of models of obesity in rats, including rats with hypothalamic damage resulting in obesity, force-overfed rats, genetically obese rats, and rats rendered obese through daily injections of insulin. The effects of prolonged maintenance of rats at altered body weights will also be assessed. BIBLIOGRAPHIC REFERENCES: Smith, P.H., Woods, S.C., and Porte, D.,Jr. Inhibition of insulin secretion by somatostatin: Reversal of the in vivo effect of alpha-adrenergic blockade. Diabetes, 1975, 24, 414. Vitiello, M.V., and Woods, S.C. Caffeine: Preferential consumption by rats. Pharmacology, Biochemistry and Behavior, 1975, 3, 147-149.